Abstract

Abstract

Representative soil samples were collected from a field experiment that was established in the spring of 1970, involving treatments of no-till with 336 kg ha−1 N applied annually, a no-till control (no N fertilizer) and conventional tillage with no N fertilizer. Soil-solution exchange phase interactions were studied by analysis of saturation extracts. Analyses were made after applications of KCl fertilizer at rates of 0.97, 1.94, 4.46, 8.82 mmols kg−1 soil and a constant application of NH4Cl at 5.55 mmols kg−1 soil. The major difference in soil properties among the treatments was in the organic matter content of 60.0, 44.6, and 21.6 g kg−1 at 0 to 50 mm depth for the no-till-high N, no-till-control and conventional tillage with no N, respectively. Results of the study also demonstrate that no-till-high N maintained a higher concentration of Ca2+, Mg2+, K+ and NH+4 in both the solution and exchange phase. Exchange sites of soils under no-tillage management exhibited lower affinity for K+ and NH+4 than do soils under conventional tillage. This lower affinity appeared to be correlated with the greater organic matter content of the no-till soil. Upon increased application rates of potassium, a greater proportion of the total NH+4 remained in the solution phase of the no-till than that of the conventional tillage soil system. The data also show that with increasing amounts of organic matter associated with the no-till, the selectivity coefficient for the ammonium-potassium interaction shifts in favor of potassium.

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